Workers and nearby residents alleged that five compounds from Lockheed Martin’s Orlando facility caused multiple sclerosis, Parkinson’s and other neurological diseases.
Published court opinionTL;DR
- Plaintiffs alleged that Lockheed Martin mishandled volatile organic compounds at its Sand Lake Road facility in Orlando, allowing them to enter surrounding soil, groundwater and air.
- Michael Davis alleged that workplace exposure caused his wife, Carol Davis, to develop multiple sclerosis and die. Other appellants attributed multiple sclerosis, Parkinson’s and other neurodegenerative diseases to the compounds.
- The claims required reliable expert proof of general causation: evidence that the compounds can cause the diseases at issue, before asking whether they caused any particular person’s illness.
- The district court excluded two causation experts. The Eleventh Circuit affirmed, finding no abuse of discretion in the conclusion that their methods were inadequately explained or improperly applied.
- The ruling ended Davis’s case and disposed of the DeMilt appellants’ claims. Other DeMilt plaintiffs with different illnesses still had claims pending when the opinion was issued.
- The court did not determine whether Lockheed contaminated the area, whether the appellants were exposed, or whether the alleged exposure caused their diseases.
The appellants lost at the scientific gatekeeping stage, leaving the underlying contamination and exposure allegations unresolved rather than disproved.
Transparency notice: This article is based on the Eleventh Circuit’s published opinion in the coordinated Davis and DeMilt appeals. I have attached a copy of the document at the bottom of this article!
The Facts
The two appeals grew out of claims involving Lockheed Martin’s Sand Lake Road manufacturing facility in Orlando, Florida. The plaintiffs alleged that the company mishandled volatile organic compounds, or VOCs, and permitted the chemicals to leach into nearby soil, groundwater and air.
They identified five compounds: TCE, PCE, toluene, xylene and styrene. The DeMilt appellants alleged that exposure caused multiple sclerosis, Parkinson’s or other neurodegenerative diseases. Michael Davis alleged that his wife, Carol, encountered the compounds while working for Lockheed, developed multiple sclerosis because of that exposure and later died.
The appellate opinion does not supply release dates, chemical quantities or individual exposure measurements. It describes the contamination and health connection as allegations that required admissible scientific proof.
What Lockheed Was Accused of Doing
The substantive accusation was that Lockheed mishandled toxic material at the Orlando facility and allowed it to migrate beyond the site. That alleged environmental pathway—from the facility into soil, groundwater and air—was how plaintiffs sought to connect company operations with exposures among workers and nearby residents.
The opinion does not describe the specific handling practice, disposal method or corporate decision alleged to have produced the releases. It also does not record a finding that Lockheed engaged in a joint contamination venture with Universal City Property Management, another defendant in DeMilt. Those matters were not resolved in this appeal.
Lockheed’s documented response in the opinion focused on the plaintiffs’ proof. It challenged their experts as unreliable and argued that without admissible general-causation testimony, the claims could not proceed.
What the Allegations Meant for the People Involved
The claimed consequences were serious and specific. Davis attributed Carol Davis’s multiple sclerosis and death to exposure at work. The DeMilt appellants attributed their own or close relatives’ neurological diseases to compounds allegedly released from the facility.
Those are allegations of medical causation, not findings. The appellate court did not conclude that any appellant had been exposed at a hazardous level, that the compounds caused the diseases, or that another explanation had been ruled out. It decided whether the experts had used reliable methods to establish that the substances were capable of causing the relevant conditions.
The practical consequence of losing that evidentiary issue was that these appellants could not present their causation theory to a jury. Their claims ended without a trial resolving the underlying contamination and exposure dispute.
The Proof Chain the Claims Required
A toxic-exposure claim must ordinarily cross two causation thresholds. General causation asks whether a substance can cause the kind of disease alleged. Specific causation asks whether it caused the disease of the particular plaintiff. The appellants’ cases stopped at the first threshold.
Experts can establish general causation through epidemiological evidence, a dose-response relationship or a comparison with the disease’s background risk. Epidemiology looks for disease patterns in populations and then asks whether an observed association is genuinely causal rather than the product of chance, bias or another explanation. Dose-response analysis asks whether changes in exposure correspond with changes in risk. Background risk provides the baseline rate of disease among people without the exposure at issue.
The separate concurrence emphasized another requirement in cases of this kind: plaintiffs need evidence of the exposure level that is hazardous to humans generally. The appellate majority’s decision, however, turned on how the two experts explained and applied their chosen methods.
Why the Expert Evidence Failed
Dr. Daniel Kantor’s weight-of-the-evidence analysis
Dr. Daniel Kantor used an epidemiological approach and concluded that the five compounds, individually and in mixtures, were capable of causing the plaintiffs’ diseases. He described this as a “weight of the evidence” opinion, a method that considers a range of studies and competing explanations before identifying the best explanation for an observed association.
The appeals court assumed, without deciding, that Kantor had reliably identified some association between the compounds and the neurological conditions. The problem arose at the next step: explaining why that association should be treated as causal.
Kantor disclosed some search terms and identified studies supporting his conclusion, but the court said he did not explain all his search criteria, how he sorted the studies, how he weighed relevant factors or how he ranked competing explanations. A flexible method, the court reasoned, still needs a visible analytical path between the underlying studies and the conclusion.
Kantor also said his review satisfied the nine Bradford Hill factors. Those factors examine timing, strength of association, dose-response, replication, biological plausibility, alternative explanations, what happens after exposure stops, specificity and consistency with other knowledge. No single factor decides causation.
His initial report did not analyze them. His rebuttal briefly applied them to one study even though the opinion relied on numerous studies. The district court regarded that discussion as too cursory, and the appeals court held that this conclusion was within the trial judge’s discretion.
Dr. Ronald Kendall’s reliance on other experts
Dr. Ronald Kendall offered two relevant opinions. First, he concluded that chronic exposure to mixtures of the compounds could cause the plaintiffs’ illnesses. Second, he concluded that people in ZIP codes near the Lockheed facility faced a higher risk involving central nervous system diseases than people farther away.
For the first opinion, the court found that Kendall largely adopted the work of Kantor and other experts without explaining an independent method. Citing reports and “the science” was not enough to show how he moved from data to a causal conclusion.
For the second, Kendall relied on statistical work by Dr. Charles Cowan. Cowan had found statistically significant higher mortality rates associated with central nervous system diseases and Parkinson’s in a ZIP code around the facility compared with Orange County mortality rates. The court did not say that this statistical result was fabricated. It held that the comparison did not perform the background-risk analysis needed to prove general causation.
| Expert | Evidence or method offered | Why the court found it insufficient |
|---|---|---|
| Daniel Kantor | Epidemiological studies, a weight-of-the-evidence approach and a later claim that the review satisfied the Bradford Hill factors. | He did not adequately explain how studies and competing explanations were weighed, and his Bradford Hill discussion was brief and limited to one study. |
| Ronald Kendall | Other experts’ reports and ZIP-code mortality comparisons based on Cowan’s statistical analysis. | The causal opinion largely adopted other experts’ conclusions. The ZIP-code comparison did not separate exposed from unexposed populations, used mortality rather than disease rates and lacked exposure-level data. |
What the ZIP-Code Pattern Could Not Prove
The ZIP-code evidence was one of the most concrete data points described in the opinion. Cowan’s analysis found higher mortality rates associated with central nervous system diseases and Parkinson’s in the ZIP code around the Lockheed facility.
Geographic proximity, however, did not establish who was exposed or at what level. The comparison also measured deaths rather than how often people developed the diseases. A valid background-risk analysis, the court said, needed to compare disease rates among exposed and unexposed populations. Neither Cowan nor Kendall had the exposure data required to make that comparison.
A statistically significant geographic pattern remained in the record, but the court held that it could not substitute for evidence identifying exposure and comparing disease risk.
“Because the experts did not reliably apply their methodologies and without those experts the plaintiffs lacked general causation evidence, the district court did not abuse its discretion in determining that their testimony was unreliable and granting summary judgment.”
Eleventh Circuit majority opinion in Davis v. Lockheed Martin and the coordinated DeMilt appeal.
The decision was not a finding that the alleged releases never occurred. It was not a finding that no appellant encountered the compounds. Nor was it a scientific determination that the compounds can never cause neurological injury. The holding was narrower: these experts had not reliably applied their methods, and without their testimony the appellants lacked evidence for a legally required step in the causal chain.
The source document for this investigation is attached below.
